1. Field of the Invention
The present invention relates to the separation of aquatic life from water. More particularly it relates to an apparatus and method configured for repositioning juvenile salmonid fishes and other aquatic life from water approaching hydroelectric dams or similar man made obstructions, into the water on the lower level downstream of such hydroelectric dams.
2. Prior Art
Fish, much like birds and other migratory animals, rely on natural instincts during seasons of reproduction for their migration from rearing areas in the lower reaches of freshwater system lakes and rivers or from the ocean for anadromous species such as Pacific salmon, back to spawning grounds normally further upstream in freshwater rivers and their tributaries. The next generation of juvenile fish then normally migrates downstream to rearing habitats used by their parents. In this cycle of life which has existed for thousands of years, fish travel in both directions through rivers which provide them a means and route for swimming passage to and from rearing habitats oceans from their breeding/spawning grounds further upstream, rivers, or lakes. In their ultimate quest for spawning and continuing the species, adult fish will travel upstream from the ocean or other water bodies downstream of potential barriers such as hydroelectric dams and the like, to the calm streams and tributaries above such hydroelectric dams, to eventually spawn and ultimately produce juveniles of the next generation. Once these juvenile fish have reached a threshold age or size, their instincts cause them to migrate downstream to rearing habitats where they will grow larger, eventually maturing and become of sufficient size and age to spawn. At that point, the fish which previously reached rearing habitats by traversing past hydroelectric dams and man made lakes, will reverse their original course and endeavor on a hazardous path of travel to home back to the streams and waterways where they originally were spawned.
This natural cycle of such fish ensures their survival as well as the survival of surrounding ecosystems. However, as can be ascertained, even in the best of times, the path of travel from small streams and tributaries to downstream habitats including the ocean for anadromous salmonid, and back again, is hazardous even under the best of conditions on an uninterrupted pathway there between. Man made dams however, offer a major obstacle for fish to traverse downstream as well as upstream in their journey, and thus cause a substantial impediment to this vital cycle. Humans have in recent decades, subsequent to the placement of dams on streams and rivers, recognized the importance of this cycle, and many attempts have been made to remedy the problems encountered by fish in their traverse past dams and other man made obstructions.
A hydroelectric power generating dam typically includes an intake located at position adjacent to the dam and upstream in the forebay portion of reservoir formed behind the dam. Such dams also have an outlet termed the tailrace at a downstream location, potentially hundreds of feet lower than the water upstream of the dam. At the base of the dam, in-between these two water bodies, one or more turbines are generally located in a conduit communicating between water flowing from upstream to downstream levels. The energy of falling water under hydraulic (water) pressure, generally turns the turbine which in turn spins an attached hydroelectric generator, thereby harnessing the energy of water falling to the lower level to generate hydroelectric power.
A grate or other screen is often located at the intake in the upstream reservoir to prevent aquatic life, especially juvenile salmonid fish, and debris from entering the turbine since such a traverse will most certainly kill the fish that are unfortunate enough to encounter the blades of the turbine. This is only of concern during downstream migration of the small fish heading to the ocean as efforts to return upstream have been ongoing through the use of fish ladders that allow fish to traverse upstream past the dams which block their path.
In moving the downstream migrating fish from upper water levels in lakes and reservoirs, to the lower water levels below dams, it is of course the goal to keep a maximum number of fish alive. To that end, many attempts have been made to re-route or re-direct the fish away from the conduits leading to dam turbines, and to the water at lower elevation levels downstream.
In a common means for such fish separation and transport to the lower downstream elevation, the fish are separated from water headed to the turbine with screens. They are thereafter collected in tanks which allow for their transport to the water below the dam at lower elevation levels by pipeline or truck. Commonly, fish are gathered in the upstream reservoir, deposited in a tank which is either on or engaged upon a truck, and then transported to the down stream location. Once at the lower elevation the fish are reunited with the waterway.
This arduous path, as can be imagined, can cause very serious problems. One recently identified problem occurs when the fish experience a large interruption in their downward migration from the reservoir behind a dam, to the waters at lower elevation. When fish are transported many miles downstream of the dam and released, and thereby do not actually swim and experience the distance between the point they were gathered into the truck, and the point they are placed back into the river downstream. It has recently been identified, that this trucking of fish can cause a lapse of instinctive migration during the transport period. Not having experienced being in the entire waterway downstream, the fish may lack the ability to follow the pathway back to the spawning grounds during a return trip reducing the number of spawners in the next generation, and causing fish to stray and spawn in the wrong streams and habitats, thereby reducing the adaptation of the fish populations that are native to these habitats. Furthermore, the combination of crowding and stress in transport tanks and problems keeping proper temperature and oxygen levels in tanks transport tanks can cause injury and/or delayed loss of life to the transported fish.
Another means is to simply create a manmade stream or river to bypass the dam and allow the fish to rely on instinctive abilities alone as seen in U.S. Pat. No. 6,652,189 to Burns, II. This however is not economical or practical when upstream and downstream locations are miles apart.
Further prior art attempts are seen but similarly fall short. U.S. Pat. No. 5,660,499 to Bethune teaches a fish siphon and overpass to transport fish upstream and downstream. Bethune however employs many moving parts that may require routine as well as unexpected maintenance that only adds to the costs and time associated with current hydroelectric power systems. Bethune discloses a siphon that may require the transport of fish through great vertical distances without care given to fish safety. Environmental regulations limit the speed at which fish can be transported through flow channels and Bethune does not address this. Furthermore, since many dams employ successful fish ladders for upstream migration as previously mentioned, the need for both downstream and upstream migration passageways at the dam site itself is unnecessary.
U.S. Pat. Nos. 6,394,699 to Neufeld, and 6,273,639 to Eikrem et. al. teach similar means to bypass dams and other manmade obstructions. They too fall short in that many moving parts are employed and may require a complete overhaul of an existing dam if they are intended to be used.
As such there is a continuing and unmet need for a simple and low maintenance device and method allowing for the elevational transport of fish and other aquatic life, from higher level waters above a hydroelectric dam or other manmade obstruction, to the lower elevation waters downstream. Such a device should effectively not scare or cause the fish to avoid it and should employ natural currents to encourage the fish within the passageway of the device to traverse there through in a manner that is concurrent to the instinctive nature of the fish. Such a device should also be safe and comply with environmental regulations. Finally, such a device should be easily installed and be adaptable to existing dam structures, and the many different traverses of elevation fish heading downstream must endure.